/* packet-mactelnet.c
 * Routines for MAC-Telnet dissection
 * Copyright 2010, Haakon Nessjoen <haakon.nessjoen@gmail.com>
 *
 * $Id: packet-mactelnet.c 36042 2011-02-24 06:22:52Z jake $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/*
 * Thanks to "omniflux" for dissecting the protocol by hand before me.
 * http://www.omniflux.com/devel/mikrotik/Mikrotik_MAC_Telnet_Procotol.txt
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <glib.h>
#include <string.h>

#include <epan/packet.h>
#include <epan/prefs.h>
#include <epan/addr_resolv.h>

#define PROTO_TAG_MACTELNET "MAC-Telnet"

void proto_reg_handoff_mactelnet(void);

/* Initialize the protocol and registered fields */
static gint proto_mactelnet = -1;
static gint hf_mactelnet_control_packet = -1;
static gint hf_mactelnet_type = -1;
static gint hf_mactelnet_protocolver = -1;
static gint hf_mactelnet_source_mac = -1;
static gint hf_mactelnet_destination_mac = -1;
static gint hf_mactelnet_session_id = -1;
static gint hf_mactelnet_client_type = -1;
static gint hf_mactelnet_databytes = -1;
static gint hf_mactelnet_datatype = -1;
static gint hf_mactelnet_control = -1;
static gint hf_mactelnet_control_length = -1;
static gint hf_mactelnet_control_encryption_key = -1;
static gint hf_mactelnet_control_password = -1;
static gint hf_mactelnet_control_username = -1;
static gint hf_mactelnet_control_terminal = -1;
static gint hf_mactelnet_control_width = -1;
static gint hf_mactelnet_control_height = -1;

/* Global port preference */
static guint global_mactelnet_port = 20561;

/* Control packet definition */
static const guint32 control_packet = 0x563412FF;

/* Initialize the subtree pointers */
static gint ett_mactelnet = -1;
static gint ett_mactelnet_control = -1;

static dissector_handle_t data_handle;

/* Packet types */
static const value_string packettypenames[] = {
	{ 0, "Start session" },
	{ 1, "Data" },
	{ 2, "Acknowledge" },
	{ 4, "Ping request" },
	{ 5, "Ping response" },
	{ 255, "End session" },
	{ 0, NULL }
};

/* Known client types */
static const value_string clienttypenames[] = {
	{ 0x0015, "MAC Telnet" },
	{ 0x0f90, "Winbox" },
	{ 0, NULL }
};

/* Known control-packet types */
static const value_string controlpackettypenames[] = {
	{ 0, "Begin authentication" },
	{ 1, "Encryption key" },
	{ 2, "Password" },
	{ 3, "Username" },
	{ 4, "Terminal type" },
	{ 5, "Terminal width" },
	{ 6, "Terminal height" },
	{ 9, "End authentication" },
	{ 0, NULL }
};


static int
dissect_mactelnet(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
	proto_item *mactelnet_item;
	proto_tree *mactelnet_tree;
	proto_item *mactelnet_control_item;
	proto_tree *mactelnet_control_tree;
	int foundping = -1;
	int foundclient = -1;
	int foundserver = -1;
	guint16 type;

	/* Check that there's enough data */
	if (tvb_length(tvb) < 18)
		return 0;

	/* Make entries in Protocol column and Info column on summary display */
	col_set_str(pinfo->cinfo, COL_PROTOCOL, PROTO_TAG_MACTELNET);

	/*  Get the type byte */
	type = tvb_get_guint8(tvb, 1);

	if ((type == 4 || type == 5)) { /* Ping */
		foundping = 1;
	} else {
		int i = 0;
		while (clienttypenames[i].strptr != NULL) {
			if (tvb_get_ntohs(tvb, 14) == clienttypenames[i].value) {
				foundserver = i;
				break;
			}
			if (tvb_get_ntohs(tvb, 16) == clienttypenames[i].value) {
				foundclient = i;
				break;
			}
			i++;
		}
	}

	/* Not a mactelnet packet */
	if (foundping < 0 && foundclient < 0 && foundserver < 0) {
		return 0;
	}

	col_add_fstr(pinfo->cinfo, COL_INFO, "%s > %s Direction: %s Type: %s",
		     tvb_ether_to_str(tvb, 2),
		     tvb_ether_to_str(tvb, 8),
		     (foundclient >= 0 || type == 4 ? "Client->Server" : "Server->Client" ),
		     val_to_str(type, packettypenames, "Unknown Type:0x%02x")
	);

	if (tree) {
		guint32 offset = 0;

		/* create display subtree for the protocol */
		mactelnet_item = proto_tree_add_item(tree, proto_mactelnet, tvb, 0, -1, ENC_NA);
		mactelnet_tree = proto_item_add_subtree(mactelnet_item, ett_mactelnet);

		/* ver(1) */
		proto_tree_add_item(mactelnet_tree, hf_mactelnet_protocolver, tvb, offset, 1, ENC_NA);
		offset++;

		/* ptype(1) */
		proto_tree_add_item(mactelnet_tree, hf_mactelnet_type, tvb, offset, 1, ENC_NA);
		offset++;

		/* saddr(6) */
		proto_tree_add_item(mactelnet_tree, hf_mactelnet_source_mac, tvb, offset, 6, ENC_NA);
		offset += 6;

		/* dstaddr(6) */
		proto_tree_add_item(mactelnet_tree, hf_mactelnet_destination_mac, tvb, offset, 6, ENC_NA);
		offset += 6;

		if (foundserver >= 0) {
			/* Server to client */

			/* sessionid(2) */
			proto_tree_add_item(mactelnet_tree, hf_mactelnet_session_id, tvb, offset+2, 2, ENC_BIG_ENDIAN);
			offset += 2;

			/* clienttype(2) */
			proto_tree_add_item(mactelnet_tree, hf_mactelnet_client_type, tvb, offset-2, 2, ENC_BIG_ENDIAN);
			offset += 2;
		} else if (foundclient >= 0) {
			/* Client to server */

			/* sessionid(2) */
			proto_tree_add_item(mactelnet_tree, hf_mactelnet_session_id, tvb, offset, 2, ENC_BIG_ENDIAN);
			offset += 2;

			/* clienttype(2) */
			proto_tree_add_item(mactelnet_tree, hf_mactelnet_client_type, tvb, offset, 2, ENC_BIG_ENDIAN);
			offset += 2;
		} else if (foundping >= 0) {
			/* Skip empty data */
			offset += 4;
		}

		if (foundping < 0) {
			/* counter(4) */
			proto_tree_add_item(mactelnet_tree, hf_mactelnet_databytes, tvb, offset, 4, ENC_BIG_ENDIAN);
			offset += 4;
		}

		/* Data packets only */
		if (type == 1) {
			while(tvb_reported_length_remaining(tvb, offset) > 0) {
				if (tvb_reported_length_remaining(tvb, offset) > 4 && tvb_get_ntohl(tvb, offset) == control_packet) {
					guint8 datatype;
					guint32 datalength;

					/* Add subtree for control packet */
					mactelnet_control_item = proto_tree_add_item(mactelnet_tree, hf_mactelnet_control, tvb, offset, -1, ENC_NA);
					mactelnet_control_tree = proto_item_add_subtree(mactelnet_control_item, ett_mactelnet);
					/* Control packet magic number (4) */
					proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_packet, tvb, offset, 4, ENC_BIG_ENDIAN);
					offset += 4;

					/* Control packet type (1) */
	 				datatype = tvb_get_guint8(tvb, offset);
					proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_datatype, tvb, offset, 1, ENC_NA);
					offset++;

					/* Control packet length (4) */
					datalength = tvb_get_ntohl(tvb, offset);
					proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_length, tvb, offset, 4, ENC_BIG_ENDIAN);
					offset += 4;

					switch (datatype) {
						case 1: /* Encryption Key */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_encryption_key, tvb, offset, datalength, ENC_NA);
							break;

						case 2: /* Password */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_password, tvb, offset, datalength, ENC_NA);
							break;

						case 3: /* Username */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_username, tvb, offset, datalength, ENC_NA);
							break;

						case 4: /* Terminal type */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_terminal, tvb, offset, datalength, ENC_NA);
							break;

						case 5: /* Terminal width */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_width, tvb, offset, 2, ENC_LITTLE_ENDIAN);
							break;

						case 6: /* Terminal height */
							proto_tree_add_item(mactelnet_control_tree, hf_mactelnet_control_height, tvb, offset, 2, ENC_LITTLE_ENDIAN);
							break;

						case 9:	/* End authentication (no data) */
							break;
					}
					proto_item_set_len (mactelnet_control_item, datalength + 9);
					offset += datalength;
				} else {
					/* Data packet, let wireshark handle it */
					tvbuff_t *next_client = tvb_new_subset(tvb, offset, -1, -1);
					return call_dissector(data_handle, next_client, pinfo, mactelnet_tree);
				}
			}
		} else if (type == 4 || type == 5) {
			/* Data packet, let wireshark handle it */
			tvbuff_t *next_client = tvb_new_subset(tvb, offset, -1, -1);
			return call_dissector(data_handle, next_client, pinfo, mactelnet_tree);
		}


	}
	return tvb_reported_length(tvb);
}


void
proto_register_mactelnet(void)
{
	static hf_register_info hf[] = {
		{ &hf_mactelnet_control_packet,
		{ "Control Packet Magic Number", "mactelnet.control_packet", FT_UINT32, BASE_HEX, NULL, 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_type,
		{ "Type", "mactelnet.type", FT_UINT8, BASE_DEC, VALS(packettypenames), 0x0,
		  "Packet Type", HFILL }},
		{ &hf_mactelnet_protocolver,
		{ "Protocol Version", "mactelnet.protocol_version", FT_UINT8, BASE_DEC, NULL, 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_source_mac,
		{ "Source MAC", "mactelnet.source_mac", FT_ETHER, BASE_NONE, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_destination_mac,
		{ "Destination MAC", "mactelnet.destination_mac", FT_ETHER, BASE_NONE, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_session_id,
		{ "Session ID", "mactelnet.session_id", FT_UINT16, BASE_HEX, NULL , 0x0,
		  "Session ID for this connection", HFILL }},
		{ &hf_mactelnet_client_type,
		{ "Client Type", "mactelnet.client_type", FT_UINT16, BASE_HEX, VALS(clienttypenames) , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_databytes,
		{ "Session Data Bytes", "mactelnet.session_bytes", FT_UINT32, BASE_DEC, NULL , 0x0,
		  "Session data bytes received", HFILL }},
		{ &hf_mactelnet_datatype,
		{ "Data Packet Type", "mactelnet.data_type", FT_UINT8, BASE_HEX, VALS(controlpackettypenames) , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_control,
		{ "Control Packet", "mactelnet.control", FT_NONE, BASE_NONE, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_control_length,
		{ "Control Data Length", "mactelnet.control_length", FT_UINT32, BASE_DEC, NULL , 0x0,
		  "Control packet length", HFILL }},
		{ &hf_mactelnet_control_encryption_key,
		{ "Encryption Key", "mactelnet.control_encryptionkey", FT_BYTES, BASE_NONE, NULL , 0x0,
		  "Login encryption key", HFILL }},
		{ &hf_mactelnet_control_password,
		{ "Password MD5", "mactelnet.control_password", FT_BYTES, BASE_NONE, NULL , 0x0,
		  "Null padded MD5 password", HFILL }},
		{ &hf_mactelnet_control_username,
		{ "Username", "mactelnet.control_username", FT_STRING, BASE_NONE, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_control_terminal,
		{ "Terminal Type", "mactelnet.control_terminaltype", FT_STRING, BASE_NONE, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_control_width,
		{ "Terminal Width", "mactelnet.control_width", FT_UINT16, BASE_DEC, NULL , 0x0,
		  NULL, HFILL }},
		{ &hf_mactelnet_control_height,
		{ "Terminal Height", "mactelnet.control_height", FT_UINT16, BASE_DEC, NULL , 0x0,
		  NULL, HFILL }}
	};

	/* Setup protocol subtree array */
	static gint *ett[] = {
		&ett_mactelnet,
		&ett_mactelnet_control,
	};

	module_t *mactelnet_module;

	/* Register the protocol name and description */
	proto_mactelnet = proto_register_protocol ("MikroTik MAC-Telnet Protocol", PROTO_TAG_MACTELNET, "mactelnet");

	/* Required function calls to register the header fields and subtrees used */
	proto_register_field_array (proto_mactelnet, hf, array_length (hf));
	proto_register_subtree_array (ett, array_length (ett));

	mactelnet_module = prefs_register_protocol(proto_mactelnet, proto_reg_handoff_mactelnet);

	prefs_register_uint_preference(mactelnet_module, "port", "UDP Port",
				       "MAC-Telnet UDP port if other than the default",
				       10, &global_mactelnet_port);
}

void
proto_reg_handoff_mactelnet(void)
{
	static gboolean initialized = FALSE;
	static guint current_port;
	static dissector_handle_t mactelnet_handle;

	if (!initialized) {
		mactelnet_handle = new_create_dissector_handle(dissect_mactelnet, proto_mactelnet);
		data_handle = find_dissector("data");
		initialized = TRUE;
	} else {
		dissector_delete_uint("udp.port", current_port, mactelnet_handle);
	}

	current_port = global_mactelnet_port;
	dissector_add_uint("udp.port", current_port, mactelnet_handle);
}
